Fluorospectrophotometric Determination of Thiourea Dioxide

In the presence of heat and alkaline condition,thiourea dioxide is reduced into nitrobenzene without fluorescent effect and into aniline with strong fluorescent effect. Based on this fact,a fluorospectrophotometric method for the determination of thiourea dioxide was proposed. The optimized conditions found are as follows:① acidity of reaction solution:pH 9.6;② amount of 1.000 g·L-1 nitrobenzene solution:2 mL;③ temperature of reaction:70 ℃;④ time of heating:15 min. Linear relationship between values of fluorescence intensity and mass concentration of thiourea dioxide was kept in the range of 0.06-1.2 mg·L-1,with detection limit (3s/k) of 3.1 μg·L-1. On the base of synthetic sample of water,test for recovery was made by standard addition method;values of recovery found were in the range of 93.3%-107%.